Conventionally, a starter with a cantilever structure is disclosed in Japanese Patent Application Laid-Open Publication No. 2006-177168.
The starter includes an output shaft 100, a pinion tube 120, a one-way clutch 130, a pinion 140, and a housing 160, as shown in FIG. 5.
The output shaft 100 is driven by a motor (not shown), and the pinion tube 120 is fit to a perimeter of the output shaft 100 via bearings 110.
The one-way clutch 130 is of a roller type that transmits rotation of the output shaft 100 to the pinion tube 120, and the pinion 140 is meshed with an end of the pinion tube 120 in an anti-motor side in an axial direction (left-hand side in the drawings) in a direct spline fitting manner.
The housing 160 supports the pinion tube 120 through a bearing 150 disposed between the clutch 130 and the pinion 140.
This starter has a system that pushes out the pinion tube 120 together with the clutch 130 in the anti-motor side direction (left-hand side in the drawing) relative to the output shaft 100, and engages the pinion 140 to an engine ring gear when triggered by an electromagnetic switch (not shown).
The starter mentioned above has a composition that the clutch 130 moves together with the pinion tube 120 when pushing out the pinion tube 120 in the anti-motor side direction by the electromagnetic switch.
Therefore, the moving mass of the movable bodies (the pinion tube 120, the clutch 130, the pinion 140) has become large and this has been a target for miniaturizing the electromagnetic switch.
On the other hand, there is a starter having a cantilever structure disclosed in Japanese Patent Application Laid-Open Publication No. 2007-146759.
In this starter, as shown in FIG. 6, the pinion shaft 170 is disposed in a helical spline fitting manner movable in an axial direction to the inner tube 131 of the clutch 130, and the pinion 140 is attached to an end of the pinion shaft 170 on an anti-motor side in the axial direction.
With this composition, since the clutch 130 does not move when pushing out the pinion shaft 170 in the anti-motor side direction by the electromagnetic switch, as compared with the starter of '168, the moving mass of the movable bodies (the pinion shaft 170, the pinion 140) can be made small.
As a result, it is possible to attain the miniaturization of the electromagnetic switch that generates the attraction force for pushing out the movable bodies.
In recent years, vehicles employing an idling stop system (ISS) that stops fuel injection to an engine to stop the engine automatically when the vehicle stops at a traffic light or during a traffic jam, etc. are increasing.
In the vehicles that employ the ISS, as compared with the vehicles that do not employ the ISS, the frequency of starting the engine increases sharply, while a number of times of operating the starter also increases sharply.
As more and more vehicles are using ISS, there is high demand for starters having well-aligned output shafts 100 and pinion tubes 120, to extend the life of the starter.